The instant invention relates to a device to piece a yarn on an open-end spinning device, having a open-end spinning element, a yarn draw-off pipe, a winding device, a feeding device to feed a yarn end to the yarn draw-off pipe, a cutting device to cut the yarn to a defined length and with a drive arrangement to move the feeding device from a rest position via a yarn receiving position and a cutting position above the yarn draw-off pipe and beyond into a yarn insertion position, as well as a process for piecing a yarn by means of such a device.
In a known device, (German Patent No. DE 3,417,331 A1) for the piecing of a yarn, the yarn mover as well as the cutting device can be moved from a rest position so as to receive the yarn, to cut it to size, to present it to the yarn draw-off pipe and finally to release it. The yarn mover and the cutting device are movably mounted on a carriage, and are driven at set translation ratios by one and the same drive installed on the carriage.
In practice, when different materials are to be spun, the spinning rotor is often replaced by one with a different diameter. If the yarn back-feeding length is not adapted to the different diameter of the spinning rotor (or to the size of another open-end spinning element), there is a danger that the piecing operation will fail or that the piecing joint may not lie within established tolerances. Setting the yarn back-feeding length is, however, not possible with the known device, as either the cutting of the yarn would not be ensured or the cutting device could come into the area of the yarn draw-off pipe.